In our earlier Australian Patent specification No. 542,978 there is described a planter unit attached to the rear bar of a cultivator. The tyne depth is adjustable, with a depth of penetration being controlled by a compaction wheel.
However with changing farming techniques, there developed a need for a more specialised seeding machine for seeding into trash with minimum or no tillage to conventional tillage leaving maximum trash on top of the soil. Reference is also made to our earlier Australian Pat. No. 544,879 (U.S. Pat. No. 4,506,609) for an improved trash seeder.
As most farmers are now using minimum or full tillage methods but leaving a maximum amount of trash on the surface, it has been found that a leading coulter is not required.
However in Australian Pat. No. 544,879 (U.S. Pat. No. 4,506,609) the frame of the machine is carried on the front wheels and all the coulters and press wheels, it has been found that by removing the coulters, problems arise due to the construction, for when the tyne jumps an obstruction or when excessive pressure is applied to the tyne forcing the tyne out of the ground, the press wheel is also lifted off the ground. This prevents the press wheel maintaining contact with and/or pressure on the ground and when the tyne jumps and the press wheel is lifted off the ground, the controlled depth of the seeding tyne point is lost in relation to the depth wheel which enables the tyne to penetrate deeper into the ground as it clears the obstruction.
It is an object of this invention to overcome the above problems.